WO2011040752A2

WO2011040752A2 - Conductive polymer adhesive using nanofiber and method for preparing the same

Info

Publication number: WO2011040752A2
Application number: PCT/KR2010/006623
Authority: WO
Inventors: Kyung Wook Paik; Chang Kyu Chung; Kyoung Lim Suk
Original assignee: Korea Advanced Institute of Science and Technology KAIST
Current assignee: Korea Advanced Institute of Science and Technology KAIST
Priority date: 2009-09-29
Filing date: 2010-09-29
Publication date: 2011-04-07
Anticipated expiration: 2012-03-29
Also published as: JP2013506260A; JP5496343B2; WO2011040752A3

Abstract

Disclosed is an adhesive for electronic packaging component for selectively conducting electrical connection parts of the electronic components, wherein a non-conductive polymer nanofiber structure having an irregularly shaped net structure is included in one or two or more adhesive layer, and a space defined by the adjacent nanofiber structures includes a portion in which one or more conductive particle is distributed. The adhesive prevents the free flow of the conductive particles in the polymer resin by suppressing the flow of the polymer resin and the flow of the conductive particle and has excellent mechanical strength by having a composite structure of the polymer resin and the polymer nanofiber structure having a net structure.

Description

Title of Invention: CONDUCTIVE POLYMER ADHESIVE USING NANOFIBER AND METHOD FOR PREPARING THE SAME

Technical Field

[1] The present invention relates to an adhesive for electronic packaging component to selectively conduct among electrical connection parts of electronic components, and more particularly, a conductive polymer adhesive using a nanofiber effectively suppressing flowing of conductive particles in a polymer resin at the time of bonding electronic components and having excellent thermal-mechanical characteristics, and a method for preparing the same.

Background Art

[2] An adhesive used for packaging electronic devices or electronic components may be classified into a film and a paste according to a used method or may be classified into a conductive adhesive, an anisotropic conductive adhesive, and a non-conductive adhesive according to whether or not it includes conductive particles. Generally, an adhesive may be classified into an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), a non-conductive film (NCF), and a non-conductive paste (NCP).

[3] Adhesives in a film type (ACF and NCF) and adhesives in a paste type (ACP and

NCP) are largely different from each other in terms of the type and compositions thereof. The ACF includes an organic solvent assisting coating performance so that it can be coated in a film type. The ACF is commercialized after it is coated in a film and the organic solvent is dried.

[4] Unlike the film, since the ACP is directly applied on a substrate by a dispensing method, or the like, to package electronic devices, such as a flip chip, etc., it does not include an organic solvent to prevent bubble from being generated therein. In addition, the ACP is commercialized by being dipped in a syringe in a paste type.

[5] The adhesives ACF and NCF in a film type use an insulating polymer resin to

perform mechanical connection among electronic components due to thermosetting of the polymer resin. In this case, the ACF further includes conductive particles dispersed in the polymer resin in order to achieve selective electrical connection among electrodes of electronic components, together with the mechanical connection.

[6] As the polymer resin, epoxy, polyimide, silicon, acrylic, polyester, or polysulfone resin are used. As the conductive particles, fine particles, such as intrinsically conductive polymer, or the like, coated with metals such as silver, gold, copper, nickel, carbon, etc., are used. The types of the conductive particles may be changed according to the field of use and the conductive particles include non-conductive particles in order to reduce thermal expansion coefficients.

[7] In particular, the connection method among the electronic components using the

ACF is a lead free process that has replaced a soldering process. The connection method is a clean, simple, eco-friendly, and thermally stable process since there is no need to instantly apply high temperature to products (low temperature process).

Further, the connection method uses an inexpensive substrate such as a glass substrate or a polyester flex, etc., to lower process costs and uses fine conductive particles to perform electrical connection, thereby making it possible to implement ultrafine electrode pitches.

[8] Owing to theses advantages, the adhesives ACF and NCF in a film type have been used for packaging a display such as a smart card, a liquid crystal display (LCD), a plasma display panel (PDP) and an organic light emitting diode (OLED). Further, the adhesives ACF and NCF have been used for packaging computer, mobile phones, communication systems, etc.

[9] When packaging electronic components using the adhesives ACF and NCF in a film type, viscosity of adhesive and adhesive flow during an adhering process are very important technically. *

[10] For example, when one component having a structure, such as electrical wirings (Cu trace), metal bumps, etc., is bonded to other components by using an adhesive, the adhesive is rapidly discharged to the outside through a valley or a path between the electrical wirings at the time of bonding if the viscosity of the adhesive is too low, such that it does not fully fill an entire space between two components, thereby causing void or bubble. On the other hand, if the viscosity of the adhesive, the adhesive doesnot fully fill fine rugged portions existing on the surface of the component, such that portions of the components may not be bonded. Therefore, the adhesive flow at the time of bonding is an important factor, which can control the flowability of the polymer resin while improving the thermal-mechanical characteristics of the adhesive.

[11] Further, in the case of the ACF, the conductive particles move by the flow of the thermosetting polymer resin at the time of the thermal compression. Therefore, in order to prevent the open, a large amount of cdnductive particles should be used. Further, in order to prevent a shor there is a solution in that conductive particles having a core shell structure surrounding the outside with the non-conductive material or a mixture of the conductive particles and the non-conductive particles should be used.

[12] As a demand for the ultrafine pitch connection is increased, a technology of

preventing conduction between the electrodes while performing stable and selective conduction is on the rise. Disclosure of Invention

Technical Problem

[13] Therefore, an object of the present invention performs an adhesive preventing

conduction between unwanted electrodes while performing stable and selective conduction between desired electrodes even in ultrafine pitches.

[14] Another object of the present invention provides a conductive adhesive improving electrical insulation by effectively filling fine voids and suppressing flow of conductive particles in a polymer resin between electronic components having fine rugged portions or curved portions existing on the surface of electronic components.

[15] Another object of the present invention provides an adhesive having excellent mechanical strength and performing selective conduction with a small amount of conductive particles without damaging performance of an adhesive.

Solution to Problem

[16] According to an aspect of the present invention, there is provided an adhesive for electronic packaging component for selectively conducting electrical connection parts of theelectronic components, wherein a non-conductive polymer nanofiber structure having an irregularly shaped net structure is included in on or two or more adhesive layer.

[17] A space defined by the adjacent nanofiber structures may include a portion in which one or more conductive particle is distributed or the nanofiber structures may contain at least one conductive particle.

[ 18] The conductive particles included in the adhesive for electronic packaging

component according to the present invention limits the flow thereof by the nanofiber structure, thereby providing selective conduction between electronic components.

[19] The adhesive layer may include an anisotropic conductive film (ACF), a non- conductive film (NCF), or a combined stacked type film formed by combining them.

[20] According to another aspect of the present invention, there is provided a method for preparing an adhesive for electronic packaging component, comprising:

[21] (a) forming a polymer nanofiber structure formed by physically tangling a non- conductive polymer nanofiber on a metal foil, for example, an aluminum foil by electro-spinning a non-conductive polymer solution;

[22] (b) stacking a polymer nanofiber structure formed on the metal foil on a stacking film on which an adhesive film and a releasing film are stacked and inserting a polymer nanofiber structure into the adhesive film by applying heat and pressure; and

[23] (c) physically removing the metal foil.

[24] According to another 'aspect of the present invention, there is provided a method for preparing an adhesive for electronic packaging component, comprising: [25] (a) stacking a non-conductive polymer nanofiber structure formed by physically tangling a non-conductive polymer nanofiber by electro-spinning a non-conductive polymer solution on a rear surface of a first releasing film of a first stacking film on which the first adhesive film and the first releasing film are stacked;

[26] (b) stacking a second stacking film, on which the second adhesive film and the

second releasing film are stacked, on the upperportion ef the nanofiber structure so that the nanofiber structure contacts the second adhesive film; and

[27] (c) inserting the nanofiber structure into the first adhesive film and the second

adhesive film by laminating the first stacking film, the nanofiber structure, and the second stacking film.

[28] Applied heat and pressure in order to insert the polymer nanofiber structure having the net structure into the adhesive film may be 30 to 150°C and 0.5 to 20 MPa, respectively, and applied time may be 1 to 60 seconds.

[29] Conductive particles are included in any one or all of the adhesive films.

[30] In the present invention, the polymer nanofiber structure having the net structure may be various but preferably has a sheet shape. The diameter of the polymer nanofiber forming the nanofiber structure may be 10 to 5000 nm and weight per apparent volume is 10-⁶ to 10 ¹ g/cm³.

[31] A material of the non-conductive polymer, nanofiber forming the non-conductive polymer nanofiber structure may be one or two or more mixture selected from group consisting of polyolefin, polyamide, polyester, aramide, acrylic, polyethylene oxide (PEO), polycaprolactone, polycarbonate, polystyrene, polyethylene terephtalate, poly- bezimidazole (PBI), poly(2-hydroxyethyl methacrylate), polyvinylidene fluoride, poly(ether imide), styrene-butadiene-styrene triblock copolymer (SBS),

poly(ferrocenyldimethylsilane), polyvinyl alcohol or a mixture thereof.

Advantageous Effects of Invention

[32] As set forth above, the conductive adhesive for electronic packaging component according to the present invention includes the polymer nanofiber structure having an irregularly shaped net structure therein and has the particle particles in the space defined by the adjacent nanofiber to suppress the flow of the polymer resin and the flow of the conductive particles, thereby effectively filling the fine voids and preventing the flow of the conductive particles in the polymer resin at the time of packaging the electronic components having the fine rugged portions and the curved portions existing on the surface of the electronic components. Further, the conductive adhesive for electronic packaging component according to the present invention has a composite structure of the polymer resin and polymer nanofiber structure having the net structure, such that it has excellent mechanical strength while maintaining electrical ^■J' '

insulation between the electrodes and performs the selective conduction with a small amount of conductive particles to prevent the short.

Brief Description of Drawings

[33] Figure 1 is a view showing a nanofiber structure having an irregularly shaped net structure used when an adhesive according to the present invention is prepared and a nanofiber forming the nanofiber structure;

[34] Figure 2 is a view schematically showing main parts of an apparatus used when a nanofiber structure having a net structure used when the adhesive according to the present invention is prepared is manufactured;

[35] Figures 3 and 4 are views showing a process of inserting the nanofiber structure having the net structure according to the present invention in a target film, wherein Figure 3 is a view showing a process of bonding the nanofiber structure to one film and Figure 4 is a view showing a process of stacking and bonding the nanofiber structure between two films;

[36] Figures 5 to 7 are views showing a process of inserting the nanofiber structure having the net structure according to the present invention in a target film, wherein Figure 5 is a process of bonding a nanofiber structure to one film (ACF) having conductive particles distributed therein, Figure 6 is aprocess of bonding a nanofiber structure between the film ACF having conductive particles distributed therein and a film NCF not having conductive particles therein, Figure 7 is a process of stacking and bonding the nanofiber structure between two films having conductive particles distributed therein, respectively.

[37] Figure 8 is an optical microscope photograph showing a shape when the conductive particles are agglomerated between electrodes;

[38] Figure 9 (a) shows a scan electronic microscope photograph of PS and Figure 9 (b) is a scan electronic microscope photograprf^'of PAN; ^{' "}

[39] Figure 10 is a graph showing results obtained by measuring insulating resistance of an adhesive according to the present invention; and

[40] Figure 11 is a scan optical microscope photograph formed by breaking a sample after bonding the PAN nanofiber structure between the NCF and the ACF, putting in liquid nitrogen, and rapidly cooling it.

Best Mode for Carrying out the Invention

[41] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. The embodiments of the present invention illustrate an adhesive layer of ACF and NCF. However, the adhesive layer according to the present invention is not limited to the ACF and NCF and the adhesive layer may include any materials or sheets if it has adhesive characteristics. [42] The present invention provides a conductive adhesive for electronic packaging component for selectively conducting between electrical connection parts of electronic components. The adhesive according to the present invention has a configuration that a non-conductive polymer nanofiber structure having an irregularly shaped net structure is included in one or two or more adhesive layers or adhesive films

[43] In addition, the adhesive for electronic packaging component accordingto the present invention includes a portion in₅which one or more conductive particle is distributed in a space defined by the nanofiber structures or a portion in which one or more conductive particleis adhered to the nanofiber structures. The flow of the conductive particles included in the adhesive for electronic packaging component according to the present invention are limited by the nanofiber structure, thereby providing selective conduction between electronic components.

[44] The adhesive layer configuring a part of the adhesive according to the present

invention may include an anisotropic conductive film ACFs or a non-conductive film NCFs and a combined stacking film formed by combining the films together.

[45] In Figure 1, a polymer nanofiber structure 10 having a net structure used in the

present invention, a nanofiber 11 forming the nanofiber structure 10, and a metal foil 20 in which the nanofiber structure is electro-spinned are shown.

[46] The adhesive for electronic packaging component according to the present invention is prepared by forming the polymer nanofiber structure' 10 having a net structure formed by physically tangling the non-conductive polymer nanofiber 11 by electro- spinning the non-conductive polymer solution, stacking the nanofiber structure 10 in the adhesive film that is a insertion target, and applying heat and pressure thereto to insert the nanofiber structure 10 in the adhesive film.

[47] The nanofiber structure 10 used in the present invention has a minor axis diameter of approximately nanometer order and non-conductive characteristics The nanofiber 11 forming the nanofiber structure 10 is obtained by electro-spinning a solution in which non-conductive polymer is dissolved (non-conductive polymer solution).

[48] Figure 2 schematically shows a configuration for manufacturing a nanofiber structure 10 used in the present invention.

[49] Referring to Figure 2,₍the nanofiber structure 10 is manufactured by continuously forming the nanofiber 11 by injecting the non-conductive polymer solution into a syringe having a needle and then applyiftg pressure to the syringe while applying E- field to a discharged area and spontaneously tangling the nanofiber 11 continuously manufactured by electro-spinning.

[50] The diameter of the non-conductive polymer nanofiber 11 is controlled by the

diameter of the needle, the viscosity of the non-conductive polymer solution, the magnitude of the applied E-field, and the discharge pressure applied to the syringe. [51] The nanofiber structure 10 mjiy be formed at a metal foil £0 by generating the E-field at the discharge hole by using a metal foil 20 at the time of the electro-spinning using the non-conductive polymer solution.

[52] The polymer nanofiber structure (polymer nanofiber, nano-conductive polymer of non-conductive polymer solution used for electro-spinning) having the net structure may be made of polyolefin, polyamide, polyester, aramide, acrylic, polyethylene oxide (PEO), polycaprolactone, polycarbonate, polystyrene, polyethylene terephtalate, poly- bezimidazole (PBI), poly(2-hydroxyethyl methacrylate), polyvinylidene fluoride, poly(ether imide), styrene-butadiene-styrene triblock copolymer (SBS),

poly(ferrocenyldimethylsilane), polyacrylonitrile, polyvinyl alcohol or a mixture thereof.

[53] The nanofiber structure 10 used in the preparing method of the present invention may be a sheet. The diameter of the nanofiber structure 10 having a direct effect on the flow of the polymer resin of the adhesive ancPpaFticles included in the adhesive may be 10 to 5000 nm and the weight per apparent volume of the polymer nanofiber structure 10 that is porosity of polymer nanofiber structure 10 may be 10⁶ to lO^-1 g/cm³. In this case, the apparent volume implies a volume obtained by multiplying the width and thickness of the polymer nanofiber structure, preferably, a volume obtained by multiplying the width and thickness of the sheet shown in Figure 1.

[54] The diameter of the nanofiber 11 and the weight per apparent volume of the

nanofiber 10 suppresses the flow of the polymer resin and the flow of particles caused at the time of bonding the electronic devices using the adhesive according to the present invention due to the net structure in which the poly nanofibers are irregularly tangled with each other. Under conditions according to the present invention, pores trapped in the adhesive are not formed and the nanofiber structure 10 is uniformly inserted in the adhesive film.

[55] The diameter of the polymer iianofibef l Iⁿforming the nanofiber structure 10 may be 10 to 5000 nm. If the diameter of the nanofiber 11 is too large, the adhesion of the adhesive according to the present invention is damaged, thereby degrading the strength at the interface between the electronic devices or electronic components that are bonding targets and it is difficult to obtain an effect of suppressing the flow of polymer resin and particles by increasing the opened pores having the net structure generated by the physical tangling between the polymer nanofibers 1 1. On the other hand, if the diameter of the nanofiber 11 is too small, the flow of the polymer resin and the flowof particles are effectively suppressed but the polymer resin is not effectively filled in the fine rugged surface existing the electronic devices that are the bonding targets, such that the fine pores may be generated at the interface between the electronic device and the adhesive and it is difficult to bond the polymer nanofiber structure 10 to the adhesive film (see 31 of Figure 3) having a sheet shape by using heat and pressure.

[56] The weight per apparent volume of the polymer nanofiber structure 10 may be 10"⁶ to 10'¹ g/cm³, which is to control the viscosity of the adhesive for packaging the electronic devices manufactured according to the present invention by bonding the polymer resin of predetermined viscosity having the adhesion to the polymer nanofiber structure 10.

[57] The weight per the apparent volume of the nanofiber structure 10 may be appro- priately controlled in consideration of the presence or absence of the fine surface ruggedness, the size of the fine surface ruggedness, the presence or absence of the conductive or non-conductive particles of the adhesive film (31 of Figure 3), etc., which exists in the bonding targets, i.e., the electronic devices. However, the weight per the apparent volume of the nanofiber structure 10 may be 10^-6 to 10"¹ g/cm³ in order to effectively suppress the flow of the polymer resin and to prevent the flow of conductive particles having a size of 3 to 5 im without damaging the adhesion of the adhesive and forming the fine pores between the adhesive and the bonding targets, i.e., the electronic components.

[58] The weight per the apparent volume of the nanofiber structure 10 may be controlled by using the magnitude of the applied E-field at the time of the electro-spinning, the injection pressure applied to the syringe, the injection amount, the moving speed of the syringe or collector (metal foil) as well as may be controlled by manufacturing the sheet formed by electro-spinning the non-conductive polymer solution to mutually tangle the polymer nanofiber and then applying the pressure or the heat and pressure to the manufactured sheet.

[59] The thickness of the nanofiber structure 10 may be controlled in consideration of the inserted adhesive film (see 31 of Figure 3). At the present, in the filed of packaging the electronic components, the substantial thickness of the nanofiber structure 10 may be 10 to 5000nm based on the non-conductive adhesive film NCF or the anisotropic conductive adhesive film ACF that are manufactured, marketed and used.

[60] As described above, the method for preparing an adhesive for electronic packaging component controls the viscosity of the adhesive by using the nanofiber structure 10, not the viscosity of the polymer resin having adhesion. In addition, the adhesive is prepared by stacking the polymer nanofiber structure 10 having the sheet shape and the adhesive film (31 of Figure 2) having the sheet shape and then bonding the two sheets 10 and 31 by applying heat and pressure thereto.

[61] In more detail, as shown in Figure 3, the method (I) for preparing an adhesive

forpacking electronic components forms a laminate stacked in order of releasing film 32-adhesive film 31 -polymer nanofiber structure 10-metal foil 20 by forming the polymer nanofiber structure 10 having a sheet shape on the metal foil 20 by using the electro-spinning and then stacking the polymer nanofiber structure 10 formed on the metal foil 20 on the stacking fijr 30 on which the adhesive film 31 and the releasing film 32 are stacked. Thereafter, the adhesive for electronic packaging component are preparedby inserting the nanofiber structure 10 into the adhesive film 31 by applying heat and pressure to both sides of the releasing film 32 and the metal foil 20 of the laminate and then, physically removing the metal foil 20.

[62] In this case, Although Figure 3 shows the case in which the release film 32-adhesive film 31 -polymer nanofiber structure 10-metal foil 20 are stacked in order, the present invention may be applied to the case in which the metal foil 20-polymer nanofiber structure 10-adhesive film 31 -releasing film 32 are stacked in order.

[63] After the laminate is formed, the viscosity of the adhesive film 31 is reduced by applying heat to the laminate and the nanofiber structure 10 is inserted into the adhesive film 31 having low viscosity by applying pressure thereto.

[64] The heat applied to bond the nanofiber structure 10 to the adhesive film 31 may be 30 to 150°C, which is a temperature for iiniformly inserting the polymer nanofiber structure 10 in the adhesive film 31 without generating bubbles and damaging the adhesive of the adhesive film.

[65] The pressure applied to bond the nanofiber structure 10 to the adhesive film 31 may be 0.5 to 20 Mpa, which is a pressure of inserting the polymer nanofiber structure 10 in the adhesive film 31 having low viscosity by the above-mentioned heating without physically damaging the polymer nanofiber structure 10.

[66] When applying the heat and pressure, it is preferable that the heat and pressure be simultaneously applied.

[67] In this case, when the nanofiber structure 10 is inserted into the adhesive film 31 by applying heat and pressure thereto, as shown in Figure 3, pressure applying plates A and B may be provided^at both sides of the laminate to uniformly pressure to the laminate, wherein the pressure applying body may be a roll type, not a plate type such as A and B.

[68] After bonding the adhesive film 31 and the polymer nanofiber structure 10, the metal foil 20 is removed by a physical picking off. All the conductive metals may be used as the metal foil 20 at the time of electro-spinning, preferably, an aluminum foil is used when considering conductivity, thermal stabilization, and easy removal (flexibility) by a physical force.

[69] As shown in Figure 4, the method (II) for preparing an adhesive for electronic

packaging component according to another aspect of the present invention stacks the above-mentioned polymer nanofiber structure 10 on a first releasing film 42 of a first stacking film 40 on which the first adhesive film 41 and the first releasing film 42 are stacked and then, stacks a second staking film 50, on which the second adhesive film 51 and the second releasing film 52 are stacked, on the upper portion of the nanofiber structure 10 to bond the nanofiber structure 10 to the second adhesive film 51.

Thereafter, the nanofiber structure 10 is inserted into the first adhesive film 41 and the second adhesive film 51 by applying heat and pressure to the laminate of the first stacking film 40-the nanofiber structure 10-the second stacking film 50, thereby preparing the adhesive for electronic packaging component according to the present invention.

[70] As described above, in the method (II) for preparing an adhesive for electronic

packaging component, the nanofiber structure 10 is formed by electro-spinning a solution (non-conductive polymer solution) in which the non-conductive polymer is dissolved, similar to the foregoing description. Further, the present invention includes an adhesive formed by forming the polymer nanofiber structure 10 having the sheet shape on the metal foil 20 by using the electro-spinning and then, physically removing the metal foil 20.

[71] In the method (I) for preparing an adhesive for electronic packaging component according to the present invention, the nanofiber structure 10 of the preparing method (II) may be a sheet shape and the diameter of the polymer nanofiber 11 forming the nanofiber structure 10 having an direct effect on the flowof particles included in the polymer resin of the adhesive and the adhesive may be 10 to 5000 nm, and the weight per the apparent volume of the polymer nanofiber structure 10 that is the porosity of the polymer nanofiber structure 10 may be 10⁶ to 10"¹ g/cm³. In addition, the polymer nanofiber structure (polymer nanofiber, nano-conductive polymer of non-conductive polymer solution^'used for electro-spinning) may be made of polyolefin, polyamide, polyester, aramide, acrylic, polyethylene oxide (PEO), polycaprolactone, polycarbonate, polystyrene, polyethylene terephtalate, polybezimidazole (PBI), poly(2-hydroxyethyl methacrylate), polyvinylidene fluoride, poly(ether imide), styrene-butadiene-styrene triblock copolymer (SBS), poly(ferrocenyldimethylsilane), polyacrylonitrile, polyvinyl alcohol or a mixture thereof.

[72] In this case, unlike the above-mentioned preparing method (I), the thickness of the nanofiber structure 10 may be controlled in consideration of the thickness of two adhesive films 41 and 51 that are bonded to each other as two adhesive films 41 and 51 and the polymer nanofiber structure 10 are bonded to each other. The substantial thickness of the nanofiber structure 10 may be 10 to 5000nm based on the thickness of the non-conductive adhesive film (NCF) or the anisotropic conductive adhesive film (ACF) that are manufactured, marketed, and used in the field of packaging the electronic devices.

[73] Similar to the above-mentioned preparing method (I), when bonding the two

adhesive films 41 and 51 and the polymer nanofiber structure 10, a temperature of 30 to 150°C and a pressure,of 0.5 to 20 MPa may be applied. As shown in Figure 3, as the heat and pressure are applied Jo perform the bonding, a single adhesive film 61 is manufactured by bonding the nanofiber structure 10 to two adhesive films 41 and 51 as well as mutually bonding the two adhesive films 41 and 51.

[74] As shown in Figure 5, in the preparing method (I) of the present invention, an

adhesive film 3 forming the stacking film 30'includes an adhesive film in which conductive particles p are uniformly distributed and an adhesive 33' for a semiconductor package having anisotropic conductivity is prepared by the preparing method I according to the present invention described based on Figure 3.

[75] In the preparing method (II) of the present invention, at least one adhesive film

selected from the first adhesive film 4Γ forming the first stacking film 40' and the second adhesive film 5 forming the second stacking film 50'is an adhesive film in which the conductive particles p are uniformly distributed. Figure 6 shows the case in which the conductive particles p are uniformly distributed in the first adhesive film AY. As an adhesive 63.' suppressing the flow of the polymer, resin and the flow of the conductive particles is prepared according to the present invention, the open or the short can be prevented and the selective conduction can be made, by using the smaller amount of conductive particles.

[76] The adhesive for the semiconductor package having the anisotropic conductivity may be prepared by bonding the first adhesive film including the conductive particles p and the second adhesive film including the conductive particlesp to the nanofiber structure 10. However, according to the present invention performing the reliable selective conduction to the small amount of conductive particles by preventing the flow of conductive particles, as shown in Figure 5, the adhesive 63' for electronic packaging component having the anisotropic conductivity is prepared by disposing the polymer nanofiber structure 10 between the adhesive films (4 of Figure 5) including the conductive particle p arid the adhesive films (51 'of Figure 6) not including the conductive particles and applyingThe heat and pressure.

[77] In one exemplary embodiment, as shown in Figure 6, the adhesive film having a plurality of conductive particles included therein is bonded to the nanofiber structure by applying heat and pressure.

[78] As another exemplary embodiment, as shown in Figure 7, the adhesive according to the present invention may be prepared by disposing the nanofiber structure in the adhesive film having the plurality of conductive particles included therein and the adhesive film in which the conductive particles are not included and bonding them. At least one adhesive film selected from the first adhesive film 4rforming the first stacking film 40' and the second adhesive film 5 forming the second stacking film 50' is an adhesive film in which the conductive particles p are uniformly distributed. In Figure 7, the open or the short can be prevented and the selective conduction can be made, by using the smaller amount of conductive particles as the present invention prepares the adhesive 63 suppressing the flow of the polymer resin and the flow of the conductive particles.

[79] The adhesive for the semiconductor package having the anisotropic conductivity may be prepared by bonding the first adhesive film including the conductive particles p and the second adhesive film including the conductive particle p to the polymer nanofiber structure 10 having the net structure. However, according to the present invention performing the reliable selective conduction to the small amount of conductive particles by preventing the flow of conductive particles, as shown in Figure 5, the adhesive 63' for electronic packaging component having the anisotropic conductivity is prepared by disposing the polymer nanofiber structure 10 having the net structure between the adhesive film including the conductive particle p and the adhesive film not including the conductive particles and applying the heat and pressure, as shown in Figure 5.

[80] The above-mentioned stacking film and the first stacking film and the second

stacking film are each formed by applying a material such as epoxy, polyimide, silicon, acrylic, polyester, polysulfone resin, or the like, all of which are a non-conductive adhesive material having thermosetting, photo curing including UV or chemical curing, to the releasing film in a film type. The adhesive material may include fine particles such as silver, gold, copper, nickel, carbon, polymer coated with metal, intrinsically conductive polymer, or the like^ or conductive particles that are mixing particles thereof. The releasing^" film may be made of polyester, polyvinylidene fluoride, polyethylene terephthalate (PET), or a mixture thereof. In this case, as the stacking film, the first stacking film, and the second stacking film, products having a brand name such as CP6920F (Sony Chemical), ANISOLM (AC-7000 series etc.

Hitachi Chemical), TCG13000 series (H&S High-tech) , which are prepared and marketed by Sony Chemical, Hitachi Chemical, Cheil Industries, H&S High-tech, or the like.

Mode for the Invention

[81] Test Example

[82] Whether or not the flowability of the conductive particles p is controlled by the non- conductive polymer nanofiber structure 10 having the irregularly shaped net structure used in the present invention can be confirmed by measuring the insulating resistance between the adjacent patterns. Trie insulating resistanc£ is a measure that forms the patterns that are not electrically connected to each other to confirm that the adjacent patterns are not conducted to each other. As can be appreciated from the optical photograph of Figure 8, when the conductive particles are agglomerated or coagulated between the adjacent patterns in the case of the fine pitch package, the adjacent patterns are conducted to each other, such that the electrical short occurs. Usually, when the measured insulating resistance exceeds 10⁸Ω, it is defined that the insulation is good. If not, it is defined as short.

[83] Forming Material and Nanofiber by Electro-Spinning

[84] The nanofiber that is a measuring target of electric resistance was manufactured according to the following conditions. PS (Mw: 192000), PAN(Mw: 150000), TBAB (Fluka) listed in the following Table was available from Sigma aldrich and the electro- spinning configuration was shown in Figure 2. The optical microscope photographs were shown in (a) of Figure 9 (PS) and (b) of Figure 9 (PAN), respectively.

[85] Table 1

[Table 1]

[Table ]

[86] Preparing Adhesive according to the present invention

[87] The adhesive according to the present invention was prepared according to the

lamination conditions listed in Table 2 below.

[88] Table 2

[Table 2]

[Table ]

[89] Measure Insulating Resistance

[90] The insulted circuit ration in 20 μηι pitch by measuring the insulating resistance in the case of using the general ACF with the case of using the nanofiber ACF according to the present invention was shown in a graph of Figure 10. In this case, the insulated circuit ratio shown the ratio that the insulating resistance measuring value is stably maintained at 10⁸Ω. In the graph shown in Figure 10, COF2 represents the case of using general ACF and Nl and N2 represent the case of using the nanofiber ACF according to the present invention. It can be appreciated from the graph of Figure 10 together with the scanning optical microscope photographs of Figure 11 that the insulation between the adjacent patterns is more stable in the case of using the nanofiber ACF than in the case of using the existing ACF. The reason is that the agglomeration of the conductive particles between the adjacent patterns is relatively reduced. As a result, it can be inferred that the flow of the conductive particles can be effectively controlled by the nanofiber during bonding.

Industrial Applicability

[91] The present invention is very advantageous in electronic packaging component such as mobile phones, etc., and highly integrated electronic components requiring the selective conduction.

Claims

An adhesive for electronic packaging component for selectively conducting electrical connection parts of the electronic components, wherein a non-conductive polymer nanofiber structure having an irregularly shaped net structure is included in one or two or more adhesive layers.

The adhesive for electronic packaging component of claim 1, wherein a space defined by the adjacent nanofiber structures includes a portion in which one or more conductive particle is distributed.

The adhesive for electronic packaging component of claim 1 , wherein the nanofiber structure contains conductive particles.

The adhesive for electronic packaging component of claim 1, wherein the adhesive layer includes an anisotropic conductive film (ACF), a non-conductive film (NCF), or a combined stacked type film formed by combining the conductive film and non-conductive film.

The adhesive for electronic packaging component of claim 1, wherein the diameter of the non-c¾nductive polymer nanofiber forming the non- conductive polymer nanofiber structure is 10 to 5000 nm and weight per apparent volume of a sheet is 10"⁶ to 10"' g/cm³.

The adhesive for electronic packaging component of claim 1 , wherein a material of the non-conductive polymer nanofiber forming the non- conductive polymer nanofiber structure is one or two or more mixture selected from group consisting of polyolefin, polyamide, polyester, aramide, acrylic, polyethylene oxide (PEO), polycaprolactone, polycarbonate, polystyrene, polyethylene terephtalate, polybezimidazole (PBI), poly(2-hydroxyethyl methacrylate), polyvinylidene fluoride, poly(ether imide), styrene-butadiene-styrene triblock copolymer (SBS), poly(ferrocenyldimethylsilane), polyvinyl alcohol or a mixture thereof. A method for preparing an adhesive for electronic packaging component, comprising:^{^}

(a) forming a polymer nanofiber structure formed by physically tangling a non-conductive polymer nanofiber on a metal foil by electro- spinning a non-conductive polymer solution;

(b) stacking a polymer nanofiber structure formed on the metal foil on a stacking film on which an adhesive film and a releasing film are stacked andinserting a polymer nanofiber structure into the adhesive film by applying heat and pressure; and (c) physically removing the metal foil.

The method for preparing an adhesive for electronic packaging component of claim 7, wherein at step (b), applied heat and pressure are 30 to 150°C and 0.5 to 20 MPa, respectively, and applied time is 1 to 60 seconds.

The method for preparing an adhesive for electronic packaging component of claim 7, wherein the adhesive film includes conductive particles.

The method for preparing an adhesive for electronic packaging component of claim 7, wherein the diameter of the polymer nanofiber forming the nanofiber structure is 10 to 5000 nm and weight per apparent volume is 10-⁶ to 10"' g/cm³.

The method for preparing an adhesive for electronic packaging component of claim 7, wherein the metal foil is an aluminum foil. A method for preparing an adhesive for electronic packaging component, comprising:

(a) stacking a non-conductive polymer nanofiber structure formed by physically tangling a non-conductive polymer nanofiber by electro- spinning a non-conductive polymer solution on a rear surface of a first releasing film of a first stacking film on which the first adhesive film and the first releasing film are stacked;

(b) stacking a second stacking film, on which the second adhesive film and the second releasing film are stacked, on the upper portion of the nanofiber structure so that the nanofiber structure contacts the second adhesive film; and

(c) inserting the nanofiber structure into the first adhesive film and the second adhesive film by laminating the first stacking film, the nanofiber structure, and the second stacking film.

The method for preparing an adhesive for electronic packaging component of claim 12, wherein at step (b), heat and pressure each are 30 to 150°C and 0.5 to 20 MPa and applied time is 1 to 60 seconds. The method for preparing an adhesive for electronic packaging component of claim 12, wherein the adhesive film includes conductive particles.

The method for preparing an adhesive for electronic packaging component of claim 12, wherein the diameter of the polymer nanofiber forming the nanofiber structure is 10 to'5000 nm and weight per apparent volume is 10⁶ to 10"' g/cm³. The method for preparing an adhesive for electronic packaging component of claim 12, wherein the metal foil is an aluminum foil. A method for preparing an adhesive for electronic packaging component, comprising:

(a) forming a non-conductive polymer panofiber structure having a net structure formed by physically tangling a non-conductive polymer nanofiber by electro-spinning a non-conductive polymer solution; and

(b) inserting the non-conductive polymer nanofiber structure into any one or all of the adhesive films by disposing the non-conductive polymer nanofiber structure from step (a) on one or more adhesive film or therebetween and bonding them by applying heat and pressure thereto.

The method for preparing an adhesive for electronic packaging component of claim 17, wherein a conductive particle is included in any one of the adhesive films.

The method for preparing an adhesive for electronic packaging component of claim 17, wherein at step (b), the heat and pressure each are 30 to 150°C and 0.5 to 20 MPa and applied time is 1 to 60 seconds. The method for preparing an adhesive for electronic packaging component of claim 17, wherein the adhesive film includes conductive particles.

A method for preparing an adhesive for electronic packaging component, comprising:

(a) forming a polymer nanofiber structure containing conductive particles having a net structure formed by physically tangling a polymer nanofiber by electro-spinning a non-conductive polymer solution and conductive particles together; and

(b) inserting the polymer nanofiber structure containing conductive particles into any one or both of the adhesive films by disposing the polymer nanofiber structure from step (a) on one or more adhesive film or therebetween and bonding them by applying heat and pressure thereto. ¹